// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_V8MEMORY_H_
#define V8_V8MEMORY_H_

#include "src/globals.h"

namespace v8 {
namespace internal {

    // Memory provides an interface to 'raw' memory. It encapsulates the casts
    // that typically are needed when incompatible pointer types are used.
    // Note that this class currently relies on undefined behaviour. There is a
    // proposal (http://wg21.link/p0593r2) to make it defined behaviour though.
    template <class T>
    T& Memory(Address addr)
    {
        // {addr} must be aligned.
        DCHECK_EQ(0, addr & (alignof(T) - 1));
        return *reinterpret_cast<T*>(addr);
    }
    template <class T>
    T& Memory(byte* addr)
    {
        return Memory<T>(reinterpret_cast<Address>(addr));
    }

    template <typename V>
    static inline V ReadUnalignedValue(Address p)
    {
        ASSERT_TRIVIALLY_COPYABLE(V);
        V r;
        memcpy(&r, reinterpret_cast<void*>(p), sizeof(V));
        return r;
    }

    template <typename V>
    static inline void WriteUnalignedValue(Address p, V value)
    {
        ASSERT_TRIVIALLY_COPYABLE(V);
        memcpy(reinterpret_cast<void*>(p), &value, sizeof(V));
    }

    static inline double ReadFloatValue(Address p)
    {
        return ReadUnalignedValue<float>(p);
    }

    static inline double ReadDoubleValue(Address p)
    {
        return ReadUnalignedValue<double>(p);
    }

    static inline void WriteDoubleValue(Address p, double value)
    {
        WriteUnalignedValue(p, value);
    }

    static inline uint16_t ReadUnalignedUInt16(Address p)
    {
        return ReadUnalignedValue<uint16_t>(p);
    }

    static inline void WriteUnalignedUInt16(Address p, uint16_t value)
    {
        WriteUnalignedValue(p, value);
    }

    static inline uint32_t ReadUnalignedUInt32(Address p)
    {
        return ReadUnalignedValue<uint32_t>(p);
    }

    static inline void WriteUnalignedUInt32(Address p, uint32_t value)
    {
        WriteUnalignedValue(p, value);
    }

    template <typename V>
    static inline V ReadLittleEndianValue(Address p)
    {
#if defined(V8_TARGET_LITTLE_ENDIAN)
        return ReadUnalignedValue<V>(p);
#elif defined(V8_TARGET_BIG_ENDIAN)
        V ret {};
        const byte* src = reinterpret_cast<const byte*>(p);
        byte* dst = reinterpret_cast<byte*>(&ret);
        for (size_t i = 0; i < sizeof(V); i++) {
            dst[i] = src[sizeof(V) - i - 1];
        }
        return ret;
#endif // V8_TARGET_LITTLE_ENDIAN
    }

    template <typename V>
    static inline void WriteLittleEndianValue(Address p, V value)
    {
#if defined(V8_TARGET_LITTLE_ENDIAN)
        WriteUnalignedValue<V>(p, value);
#elif defined(V8_TARGET_BIG_ENDIAN)
        byte* src = reinterpret_cast<byte*>(&value);
        byte* dst = reinterpret_cast<byte*>(p);
        for (size_t i = 0; i < sizeof(V); i++) {
            dst[i] = src[sizeof(V) - i - 1];
        }
#endif // V8_TARGET_LITTLE_ENDIAN
    }

    template <typename V>
    static inline V ReadLittleEndianValue(V* p)
    {
        return ReadLittleEndianValue<V>(reinterpret_cast<Address>(p));
    }

    template <typename V>
    static inline void WriteLittleEndianValue(V* p, V value)
    {
        WriteLittleEndianValue<V>(reinterpret_cast<Address>(p), value);
    }

} // namespace internal
} // namespace v8

#endif // V8_V8MEMORY_H_
